This invention relates to a new and improved structure formed as a gridwork of interlocked, lightweight, injection molded plastic or injection molded structural foam plastic components. The structure may be used as an earth retaining wall by filling earth in between the plastic components of the gridwork, or the structure may be used simply as a structural wall. When used as an earth retaining wall, the earth in the structure can be stabilized by means of growing vegetation, or by means of earth retaining panels, or both. When used in conjunction with closed fascia, the structure can be used as a water wall to protect earthen banks.
Prior art structures are stabilized by means of the weight of the concrete, timber, metal beams, etc., and with the weight of the retained earth; hence, the term `gravity wall` is used to describe these structures. These prior art structures are stabilized by the rigidity of the components and also their heavy weight. Thus, the strength of the structure is related to their rigidity and weight as well as the weight of the earth which is retained by the structure.
But the use of timber, metal beams, concrete or building blocks is expensive both in terms of material cost and labor. Also, they are expensive in terms of installation costs due to the weight of the materials employed, since these heavy components require the use of large lifting cranes, heavy powered equipment and manpower.
Various publications of earth retaining wall systems include U.S. Pat. Nos. 4,514,113; 4,661,023; 4,718,792; 4,725,168; 4,798,499; 4,914,876; 4,917,543; 4,929,125; 4,930,939; 4,952,098; 4,961,673; and, 4,968,186. But, these patents involve structures which employ concrete, building blocks, steel or timber as an essential reinforcement, and these prior art components are immobilized in position.
However, when using these prior art components, the ground on which the structure is installed may shift due to water absorption, or due to earth movement such as soil subsistence or hill slides, or due to earthquake, etc. Consequently, if the structural components are in a fixed or immobilized position, they will tend to be placed under a greater degree of compressive or tensile stress, and the entire structure could fail or become badly deformed.
Hence, it is desired to provide an earth retaining system which can also function as a structural wall, and which employs inexpensive and lightweight components that may be installed quickly and inexpensively. Also, an earth retaining system is desired in which the components are adjustable, thereby enabling the structure to follow curved or straight lines, and where the components are resilient to earth movement, earthquakes, and the like.
It is also desired to provide a structure that can shift slightly vertically or horizontally to adjust to ground movement, which gives rise to the term `diaphragm wall`.
It is also desired to provide a structure which relies solely on lightweight, interlocked components as well as on the weight of earth to maintain stability.